Art of producing very thin steel and like sheets in wide strips



June 29, 1965 c. E. MAIER 3,191,291

ART OF PRODUCING VERY THIN STEEL AND LIKE SHEETS IN WIDE STRIPS 2 Sheets-Sheet 1 Filed Jan. 21, 1959 INVENTOR CuRr/s E MA/ER June 29, 1965 c. E. MAIER 3,

ART OF PRODUCING VERY THIN STEEL AND LIKE SHEETS IN WIDE STRIPS Filed Jan. 21, 1959 2 Sheets-Sheet 2 T 7 0 l h o 2/ INVENTOR CuRr/s E MA IER ATTORNEYS United States Patent Office 3,191,291 Patented June 29, 1965 3 191 291 ART or PnonUcrNi; ViZRY THIN STEEL AND LIKE SHEETS IN WIDE STRIPS Curtis E. Maier, Chicago, Ill., assignor to Continental Can Company, Inc., New York, N.Y., a corporation of New York Filed Jan. 21, 1959, Ser. No. 788,157

3 Claims. c1. 29-527 This invention relates to the production of thin sheets of steel and other work-hardening materials.

7 Steel rolling mill equipment is presently employed for reducing billets to plates and thence to sheets. In the production of so-called black plate for cans, the existing equipment can produce strip steel up to 36 inches wide and down to 0.008 inch thick (so-called 70 #/BB) at low labor and overhead costs; such sheet steel is useful for making medium sized rigid can bodies and ends, and existing converting equipment can produce cans therefrom at high speed with high labor and conversion efficiencies, in-

cluding the preparatory coating with tin or other metal,

and lithographing or other enameling operations. However, for small cans this thickness is not necessary for adequate strength: but the expense of producing gauges :thinner than 0.008 inch is so great that the cost per unit surface area is not reduced unless the can manufacturer 'is willing to accept sheets less than the customary 34 to 36 :inches maximum width. One reason is that, as the strip becomes thinner in the final cold rolling for producing a strip of the desired thickness and hardness, existing tandem -4-high mills are operating near their capacity at the last stands of the mill equipment in rolling so-called MR sheets to 0.008 inch thickness, or the harder so-called MC-T6 steel to 0.012 inch. At such thicknesses and the associated hardnesses, the roll pressures become so high that elastic flattening of the contact surface of a roll ocours, and there is so much elastic bending along the length of the roll that the Sheet edges are reduced in thickness more than the center areas. Thus, to permit rolling, the strip width is reduced and therewith the total pressure, based on the same unit pressure for the lesser width, is kept within the capability of the roll stand. It has been proposed to avoid this trouble, by first hot-rolling to a lesser gage, e.g. to half the present hot-rolled specification thickness, but in practice this does not permit reducing the final sheet thickness by a like proportion; because there .is substantially the same hardening effect by cold-rolling from 0.050 inch to 0.010 inch as there is in cold-rolling from,0.100 inch to 0.010 inch, noting that the increment of hardening is minor when the reduction is increased from 80 percent to 90 percent, and therewith the rollseparating force at 0.010 inch gage is not materially affected. Further, in practice the rolling forces are inversely related to sheet gage, so that the rolling pressures rise rapidly at very thin gages. Even the addition of another like roll stand does not overcome the problem of the extremely high roll-separating forces, and only a small further reduction can be obtained by adding further rolls in the train.

7 Another proposal is to build heavier tandem 4-high mills, using heavier columns and back-up rolls of greater diameter; so that for example the effective roll pressures, needed to overcome roll-separating forces, could be doubled over the pressures available with existing equipment. This would not reduce the elastic flattening of the work rolls, but will permit rolling down to 0.006 to 0.007 inch (55 to 60 lb. plate) in 34 inch widths. However, the amortization of such heavier mills, and the limited gain "in thinness, represent an increased overhead charge which rnust beadded to the operation expense.

have been built, but are of reversing type and hence do not Sendzimir mills show the economics needed for high tonnage production;

tandem mills require new bearing and lubrication systems for rotational speeds high enough for competition with existing 4-high tandem rolling mills. The use of smaller diameter rolls on the 4-high tandem mills, comparable to the rolls of Sendizimir mills, has not be adopted as practical; because while elastic rol-l flattening and roll friction may be reduced, noting that the metal surface speed at entrance is less than the peripheral speed of the roll, and the metal exit speed is greater than the roll speed, yet the thrust component which arises because the work roll is compressing metal at only one side of the vertical plane through the roll axis necessitates the use of two back-up rolls to support a small, long work roll: these back-up or supporting rolls are in turn limited in diameter by the available space, so that secondary back-up rolls are required. This collection of small diameter rolls, rotating at high and diiferent rotational speeds, to get the same surface speeds, constitute grave problems in the driving, bearing and lubrication of such a system. Other proposals have been made, such as increasing the number of working rolls in each stand, rolling first by the usual tandem stands and then by a Sendzimir or cluster mill wherewith the slower speed of the final mill limits the through-put for the earlier stands.

Pack-rolling has been proposed, by which two strips are superposed and passed through the rolling mill together: but in practice the entrapment of dirt and other particles between the sheets, e.g. entering with the coolant and lubricant employed in streams against the roll surfaces, have led to surface and thickness irregularities; and even to puncturing of thin strips. Further, it is difiicult to feed two separate strips accurately through the several stands, with their edges accurately matched; and point welding can occur, with consequent difl'iculty of separating the strips without damage to the surfaces, noting that quantity conversion of the strips to useful products demands that there be no necessity of visual inspection and manual discarding of imperfect areas or products.

According to the instant invention, steel strips of thicknesses of 0.006 inch and below can be prepared upon existing equipment for the widths of the equipment, without requiring the addition of special edge-guiding devices, special lubrication, or special working and backing rolls.

An illustrative practice of the invention is shown on the drawings, in which:

FIG. 1 is a perspective view of a billet having therein a core of anti-weld material;

FIG. 2 is a perspective view of a section of hot-rolled strip prepared from the billet of FIG. 1;

FIG. 3 is a perspective view on a larger scale of part gt a cold-rolled laminate strip prepared from the strip of FIG. 4 is a perspective view showing two thin sheets made by trimming the strip of FIG. 3;

FIG. 5 is a conventionalized diagram of the steps of cold-rolling the strip of FIG. 2, with surface coating before trimming, and with coiling of the thin strips produced;

FIG. 6 is a corresponding diagram, in which the thin strips are separated, cleaned, and coated before coiling;

FIG. 7 is a corresponding diagram, in which the thin strips are cleaned, annealed and given a final temper rolling pass;

FIG. 8 is a like diagram showing operations of temperrolling and electroplating the strip;

FIG. 9 is a fragmentary perspective View of the plates of FIGURE 11 after the same have been formed into a billet and hot roll-bonded together;

FIG. 10 is a sectional view on a greatly enlarged scale of parts of the sheets prepared from the billet of FIG. 9;

FIG. 11 is a perspective view of a plurality of plates aligned for forming the billet of FIG. 9 prior to the rollbonding thereof;

r 4 The strip 19 may be subjected to other operations before splitting, as can the thin laminations 20, 21 formed therefrom. For example, in FIG. 6, the strips 20, 21 are separated after leaving thesplitting device 30 and led individually through a cleaning and pickling step conventionalized as baths 35 with guide rollers 35a for leading the strip therethrough and scrubbing brushes 35b to assure by filling the core material into a channel, an openend may be sealed as by'peening or by welding a closure piece 12 to the billet. The billet 10 thusmade' has the upper and lower metal sides 13, 14 with the core 11 between them,

these sides being joined by integraledges so that the core 11 is enclosed and confined within the billet.

The billet 10 is then hot rolled. to produce a strip 16,

7 FIG. 2, having essentially the same width but being extended in'length in proportion to the reduction of thickness. The core 11 is correspondingly reduced and extended, and provides a separating, weld-preventing layer as a discontinuity extending longitudinally in. the strip and extending transversely from adjacent one longitudinal edge to adjacentthe other longitudinal edge. Also, the billet may be prep'aredzfrom hot-rolled slabs or hot-rolled coils, by cleaning, applying a resist or'antiweld material to the major part of the width of one piece, superposing another cleaned piece, Welding the edges continuously closed as by torch, electric or, hotof lamination thicknesses.

Illustratively the billet 10 may have an over-all thickness, between its upper and lower sides,-of say.8 /2- inches,

with the core 11 providing A3 to /2 inch of this, so that the metal sides 13, 14 are each 4 inches or more hick.

roll bonding, and then cold-rolling to the desired gagesremoval of residual resist. Thereafter the strips are coated, e. g. by immersion in the conventionalized molten metal 'or electroplating baths 36, followed by treatment at. bur- 'nishingrolls 37 before passing to thetake-up rolls 31, 32.

Thus the strips may be coated with tin,'zin-c, lead or other metal, ready for employment and for protection. of .the coils before use.- v a {Annealing can be effected, in a heating chamber 70 prior to slitting. In such cases, when a harder material is desired, e.g. for 'electro-platin'g, the cleaned and scrubbed stripfrom a bath of'FIG. 6 can be dried in an oven .380, and subjected (FIG. 8) to ,a temper-rolling in a 'st'and39, wherein a slight reduction of gage is effected, eg /2 to 2% in thickness or, as commonly expressed,

an elongation of a unit length of;12 inches to 12.06 to 12.24 inches. Therewith any matte -surfaces are made;

smooth and bright. Thereafter, a second cleaning is performed in a bath 35d, followed by drying in an oven 38c, electroplating 'in a bath 38d withelectrodes 38a, and reflow brightening in the "conventionalized' device. 38 as with known electroplating" processes, before being coiled at the stand 31. v, p 7 I In FIG. '7, the strips 20, :21 are passed through enamel baths 38 and then through baking devices 38a; In such cases, when an annealing hasbeen performed prior to Such a billet can be 34 inches wide and 8 feet long. ,After hot rolling to form the strip 16, FIG. 2, the total thickness can be 0.060 to'0.120 inch, with a coreresidue 11 0.001 to 0.006 inch thick, and with themetal lamination layers above and below the core residue having'a thicknessof 0.028 to 0.056 inch: therewith the billet has been lengthened t o over 1000 feet of 0.060 inch strip stock 011500 feet of 0.120 inch strip stock slightly over 34-inches wide. The integral edges 15 can originally have a Width of'% to 2 or more inches from the edges of the core 11 to the outer edge surfaces: and this dimension is closely maintained during cold-rolling.

The strip stock of FIG. 2-can thenbe fed into a cold rolling mill, FIG. 5, with four orfive tandem stands 40,

of which two are shown, as now used for rolling 0.008.

inch and thicker stock, and cold-rolled therein to form a:

about 0.004 inch thick, and are separated-by the final residual layer 22 of core material about 0.0005 or, less inch thick. The ,core material is still confined and enclosed: and the edges 15 have been flattened, but remain as integral connections andside-seals.

slitting but work-hardened smooth strips are desired, temper-rolling devices 39 may beemployed, e.g.between the point where the'laminations are separated, and the point where they receive coatings in the illustrative baths 38..

It will be noted that therolling operations can thus be immediately followed by coating operations, with prior cleaning-if desired, so thatthe product ascoiled is thereby protected against corrosion.

' The procedure also is'useful in the production of very thin strip material having cladding on one or bothsides.

Forexa'mple, in FIG. 11, the-plates for making a composite billet for producing strips'having metal cladding at both sides are shown'as comprising the upper cladding plate of stainless steel, an upper steel body plate 57, a second cladding plate 52 of stainless steel, 2. third cladding plate 53 .of stainless steel shown as formed with a cavity in its upper surface toreceive the core material 11, a lower steel bodyplate 54 shown as recessed for fitting the cupped plate 53, and a bottom cladding plate55 of stainlesssteel; The surfaces of the stainless steel, which are to be bonded, are previously provided with a thin nickel or like bonding metal layer, as by electroplating.

The parts are brought together and held by local tackiwelds 58, FIG. 9, and then hot rolled to efiectbonding of the cladding .plates50, 52 to body plate 57, of the cladding plates 53, 5 5 to the body plate 54, and of the abutting The strip 19 can now be .cut along lines parallel to,

its'edges and passing through-the residualcore layer 22 close to its lateral edges, being spaced in the illustrative example about 0.300 inch from the strip edges as shown by the line 24 in FIG. 3. Such cutting may be done by rotary slitter knives 30,-conventionally shown in FIG. 5.

The lamination-layers 20, 2 1 can then be'peeled apart, FIG. 4, with the trimmed double-thick edge portions 25 separated therefrom. The residue 22 ofthe core material, shown by stippling in FIG. 4, is very thin, and for many purposes can be'left in place.

The laminations 20, 21' are each 0.004 inch thick by about 34 inches .wide and 7000 feet long;and can be coiled for use as shown by the take-up rolls 31, 32 in FIG. ,5,

metal areas ofthe adjacent claddingplates 52, 53 whereby to enclose the resist or anti-weld core material 11. This bonded condition of thebillet 60;FIG. 9, is denoted by the dotted lines. This billet 60 can thenbe rolled to a strip 61, the edges split away, and the lamination layers separated as with the billet 10,; to form two thin strips 62, 63, EIGVIO; lllustratively, the-cladding plates 50, 52, 53,5'5'can be 0.250 inch thick, the steel body plate 57 can be, 3% inches thick, and the'body plate 54 4 inches thick formed with a /2, inch recess in its topto receive the /2 inch cup depth formed in plate 53. The core material in the cup can'be /2 inch thick. 'When these have been assembled and rolled to a final overall thickness of 0.0085

inch, :the strips 62, 63 of FIG. 10 will have a total thickness of 0.004 inch each, the'surfaces being provided by tightly bonded layers of stainless steel cladding, with each cladding layer 0.00025 inch thick. Thus a very thin and economical cladding can be provided upon a body metal layer having a width of say 34 inches and hence economical for use in can making.

Although the above illustrative practices are with two lamination layers, with a single intervening resist layer, the invention can be employed by the superposition of a greater number of pieces, separating them at the adjacent surfaces which are to be external in the cold-rolled and edge-trimmed strips, by layers of resist material. In FIG. 12, such a cold-rolled material is shown with four metal layers 73 and three resist layers 71, one of the correspondingly thick edging strips '72 being shown partly detached as in FIG. 4. When hard resist particles such as aluminum oxide are employed as a resist, the surfaces of the inner layers have a matte finish as does one surface of each outer layer: with softer-acting resists such as talc, graphite, salt or sugar, the latter three being employable when only cold-rolling is performed after assembly, the surface is smoother. If the customers specification demands smooth bright surfaces, these can be produced by the latter temper rolling described above.

In each form of practice, the billet has an internal discontinuity provided by the core of resist material which prevents welding of the laminate layers during rolling, With this material sealed against escape at the sides or ends of the billet and strip; and with this same sealing being effective to prevent penetration of solid or liquid impurities into the region between the laminate layers where such impurity may either directly adversely affect the regularity of the reduction, or by co-action with the resist prevent the extension of such resist uniformly during the rolling.

The process is useful with work-hardening metals, and and can be employed with carbon steels such as MR and MC grades, stainless steels such as 18:8, and other rollable iron alloys, to obtain wide strips having thicknesses of 0.002 to 0.003 inch Without difficulty in normal present rolling mill stands.

It will be understood that the illustrative embodiment are not restrictive, and that the invention can be employed in many ways within the scope of the appended claims.

I claim:

1. A method of producing thin wide strips of steel and like work-hardening materials comprising the steps of preparing a billet by superposing sheet steel pieces with interposed weld preventing material terminating laterally short of the longitudinal edges of the billet thereby forming two metal regions extending from end to end of the billet, welding the longitudinal edges together at spaced points along their lengths to provide sealing joinder of only the two metal regions, hot-roll bonding the longitudinal edges of the billet, cold-rolling the billet to elongate the metal and the weld-preventing material concurrently to form a rolled strip and therewith reduce the material to form laminations having a thickness of 0.002 to 0.007 inch separated by a layer of weldpreventing material for the longitudinal regions Where the metal overlies said material, annealing this strip after the cold-rolling operation, longitudinally slitting the strip through the layer of weld-preventing material along lines adjacent the lateral edges of said layer after the sheet has been annealed, separating the laminations from one another and from the connected edge portions, and thereafter, cold-temper rolling at least one of the individually annealed and separated laminations.

2. A method of producing thin wide strips of steel and like work-hardening materials comprising the steps of preparing a billet by superposing sheet steel pieces with interposed weld preventing material terminating laterally short of the longitudinal edges of the billet thereby forming two metal regions extending from end to end of the billet, welding the longitudinal edges together at spaced points along their length to provide sealing joinder of only the two metal regions, hot-roll bonding the longitudinal edges of the billet, cold-rolling the billet to elongate the metal and the weld-preventing material concurrently to form a rolled strip and therewith reduce the material to form laminations having a thickness of 0.002 to 0.007 inch separated by a layer of weld-preventing material for the longitudinal regions where the metal overlies said material, annealing this strip after the coldrolling operation, longitudinally slitting the strip through the layer of weld-preventing material along lines adjacent the lateral edges of said layer after the sheet has been annealed, separating the laminations from one another and from the connected edge portions, cleaning the annealed and separated laminations to remove the weld-preventing material, and thereafter, cold-temper rolling at least one of the individually annealed and separated laminations.

3. A method of producing thin wide strips of steel and like Work-hardening materials comprising the steps of preparing a billet by superposing sheet steel pieces with interposed weld preventing material terminating laterally short of the longitudinal edges of the billet thereby forming two metal regions extending from end to end of the billet, welding the longitudinal edges together at spaced points along their lengths to provide sealing joinder of only the two metal regions, hot-roll bonding the longitudinal edges of the billet, cold-rolling the billet to elongate the metal and the weld-preventing material concurrently to form a rolled strip and therewith reduce the material to form laminations having a thickness of 0.002 to 0.007 inch separated by a layer of Weld-preventing material for the longitudinal regions where the metal overlies said material, annealing this strip after the cold-rolling operation, longitudinally slitting the strip through the layer of weld-preventing material along lines adjacent the lateral edges of said layer after the sheet has been annealed, separating the laminations from one another and from the connected edge portions, cleaning the an nealed and separated laminations to remove the weldpreventing material, cold-temper rolling at least one of the individually annealed and separated laminations, again cleaning each lamination after the cold-temper rolling operation and thereafter, coating the individual lamination by electrodeposition.

References Cited by the Examiner UNITED STATES PATENTS 1,619,399 3/27 Brace 29-553 X 1,956,818 5/34 Acre. 2,095,837 10/37 Sandler 29529 2,117,454 5/38 Sandler 29529 2,375,224 5/45 Hensel 29-196 2,394,383 2/46 Hopkins 29-529 2,593,460 4/52 Johnson -60.7 X 2,645,842 7/53 ()rr. 2,650,162 8/53 Cape 29196 2,745,172 5/56 Townsend. 2,797,476 7/57 Sendzimir 29--528 2,957,234 10/60 Valyi 29529 X 2,975,513 3/61 Chyle 29-196.6 X 2,995,816 8/61 Ma 29528 FOREIGN PATENTS 742,192 12/ 32 France. 813,987 9/51 Germany.

OTHER REFERENCES The Marking, Shaping and Treating of Steel; US. Steel, 7th ed., 1957, page 633.

WHITMORE A. WILTZ, Primary Examiner.

NEDWIN BERGER, HYLAND BIZOT, Examiners. 

1. A METHOD OF PRODUCING THIN WIDE STRIPS OF STEEL AND LIKE WORK-HARDENING MATERIALS COMPRISING THE STEPS OF PREPARING A BILLET BY SUPERPOSING SHEET STEEL PIECES WITH INTERPOSED WELD PREVENTING MATERIAL TERMINATING LATERALLY SHORT OF THE LONGITUDINAL EDGES OF THE BILLET THEREBY FORMING TWO METAL REGIONS EXTENDING FROM END TO END OF THE BILLET, WELDING THE LONGITUDINAL EDGES TOGETHER AT SPACED POINTS ALONG THEIR LENGTHS TO PROVIDE SEALING JOINDER OF ONLY THE TWO METAL REGIONS, HOT-ROLL BONDING THE LONGITUDINAL EDGES OF THE BILLET, COLD-ROLLING THE BILLET TO ELONGATE THE METAL AND THE WELD-PREVENTING MATERIAL CONCURRENTLY TO FORM A ROLLED STRIP AND THEREWITH REDUCE THE MATERIAL TO FORM LAMINATIONS HAVING A THICKNESS OF 0.002 TO 0.007 INCH SEPARATED BY A LAYER OF WELDPREVENTING MATERIAL FOR THE LONGITUDINAL REGIONS WHERE THE METAL OVERLIES SAID MATERIAL, ANNEALING THIS STRIP AFTER THE COLD-ROLLING OPERATION, LONGITUDINALLY SLITTING THE STRIP THROUGH THE LAYER OF WELD-PREVENTING MATERIAL ALONG LINES ADJACENT THE LATERAL EDGES OF SAID LAYER AFTER THE SHEET HAS BEEN ANNEALED, SEPARATING THE LAMINATIONS FROM ONE ANOTHER AND FROM THE CONNECTED EDGE PORTIONS, AND THEREAFTER, COLD-TEMPER ROLLING AT LEAST ONE OF THE INDIVIDUALLY ANNEALED AND SEPARATED LAMINATIONS. 